Iron-porcelain insulating-bushing.



R. P. JACKSON.

IRON PORCELAIN INSULATlNG BUSHlNG.

APPLICATON FILED )UNE 9 1914. 1,199,467.

Patented Sept. 26, 1916.

INVENTOR d/ ADJaC/fa/z ATTNEY WITNESS'S: y f La/23M j@ d 7 UNITED STATESPATENT OFFICE.

RAY P. JACKSON, 0F EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TOTESTING-HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OFPENNSYLVANIA.

v IRON -PORCELAIN INSULATING-BUSHING.

Specification of Letters Patent. Patented Slept. 26, 1916,

Application filed .Tune 9, 1914. Serial No. 843,948.

l To all 'whom it may concern:

Be it known that I, RAY P. JACKSON, a citizen of the United States, anda resident of Edgewood Park, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement inIron-Porcelain Insulating-Bushings, of Which the following is aspecification.

My invention relates to electrical insulating structures, and it refersto bushings which are adapted to insulate high-potential conductors fromwalls of casings or tanks in which transformers or other electricapparatus associated with the high-potential conductors may be disposed.However', it will be understood that my invention may be utilized alsoin high-voltage outlet structures for power stations, transformersub-stations, etc., where it is necessary to bring high-potentialtransmission conductors through the walls or roofs of the sta.-` tionbuilding.

The usual porcelain insulating bushings l which have corrugated surfacesor a plu.- rality of superposed petticoats are liable to be broken whenlocated in places where they are exposed to severe mechanical shocks andstrains. To insure them a ainst breakage, porcelain insulators are o acumbersome construction in order to provide suiiicient strength toresist the strains imposed upon them. As 'a result, the weight of suchinsulators makes them dilicult to handle, and increases their cost ofconstruction. By means of my invention, vI provide an insulating bushingwhich is particularly adapted for severe service conditions, because theeX- posed petticoats are made of cast iron or some other material whichis capable of withstanding very severe mechanical shocks and strains.Furthermore,l my insulating bushing may be utilized to insulate veryhigh-voltage conductors and, at the same time, be smaller in size andsimpler in construction than insulating bushings of the usual porcelaintype heretofore constructed for similar service conditions.

For a better understanding of the nature and the scope of my invention,reference may be had to the following description andthe accompanyingdrawing in which- Figure 1 is a cross sectional view of an insulatingbushing constructed in accordance with my invention, and Fig. 2 is across sectional view showing a conductor threaded through acondenser-type bushing which, in turn, is embraced by a bushingembodying a form of my invention.

Referring to Fig. 1, a high-potential conductor 2 is embraced by abushing 3 which comprises a continuous inner tube 4i surthe rod 2 andthe transmission conductor or othervapparatus (not showin) is effectedby,

mears of any suitable means engaging the cap The portions of the bushing3 which are exposed to mechanical shocks constitute a series ofsuperposed metallic conducting members or petticoats 8 made of cast ironor other suitable material. The edge of the opening in each petticoatmerges intoa bead 9 which engages the insulating cylinders 5 at theirmid points or elbows l0. With the exception of the uppermost petticoat8, each petticoat is interposed between two adjacent and superposedcylinders 5, and is maintained rigidly in position by means of Portlandcement 11 which adheres to the metallic petticoat Sand the adjacentsurfaces of the cylinders 5. Bridging the spaces between ,adjacentpetticoats 8, are bodies 12 of insulating material which is capable ofbeing molded and has high dielectric strength, suc'h as an insulatinggum of a variety well known in the art. For maximum efficiency, thematerial l2 between each adjacent pair of the metal petticoats 8 is somolded as to provide a leakage surface therebetween which conforms tothe direction of the elecinverted substantially frusto-conical shapes,

engage the exposed surfaces of the molded material. It will beunderstood that it is not essential to have the exposed insulatingsurfaces conform to the direction of the electrostatic flow linesrepresenting the electric field between the conducting members, but, inhigh-voltage installations, it is desirable to design the insulatingbushings in accordance with this principle in order to obtain themaximum insulating strength of the bushing.'

In constructing the bushing, the adjacent porcelain cylinders 5 arebuilt up, and insulating gum 14 is interposed between adjacent surfacesof the upper half of the lower cylinder, and the lower halfy ofthe uppercylinder. The space between the rod 2 and the inner tube 4 may belikewise filled with a suitable insulating gum.

It is apparent that it will be necessary to supply each bushing with aplurality of conducting petticoats 8, insulated from one another bymeans of the nested porcelain insulators 5, the total number ofconducting members for each bushing depending upon the serviceconditions to which the bushing is -to be subjected. The conductingmembers 8 are adequately insulated from one another, and the porcelainmembers 13 are interposed therebetween to provide permanent leakagepaths of high resistance. The petticoats 8 extend laterally beyond themembers 13, thereby shielding them from rain and mechanical blows whichwould either decrease or deteriorate their insulating qualities, orlessen 'the .resistance of the leakage paths. Again, the porcelaincylinders 5 are subjected only to compressive stresses which porcelainis particularly adapted to resist.

lVhile I have shown porcelain members 13 engaging the exposed surfacesof the insulating material 12, it is not necessary that these porcelainmembers be supplied. However, it is preferable to protect the exposedsurfaces of the molded material 12, inasmuch as it may becomehoneycombed and filled with particles of dust and other matters whichwill decrease its insulating properties. Asa result, the resistance ofthe leakage path between the adjacent petticoats S will be decreasedunless the porcelain members 13 are utilized to protect the exposedsurfaces of the insulating material 12. Again, porcelain material may bereadily molded into various shapes before being glazed. This propertyparticularly adapts porcelain for use where the exposed insulatingsurface should conform to electrostatic iiow lines, as mentioned above.

Referring to Fig. 2, an inner bushing 15 of the condenser type ofconstruction, which comprises a plurality of layers of alternatelyinsulating and conducting materials, .embraces a metallic tube 16 whichconstitutes the high-potential conductor. The exposed portion of thebushing l5 is inclosed by a bushing built in accordance with myinvention. The frusto-conical end of the condenser bushing ishermetically sealed in position within the bushing 3 by means of aninsulating gum or compound 17. Inasmuch as the electrostatic stressesare equalized and the electrostatic lines are uniformly distributed byreason of the bushing 15, the porcelain members 13 which constitute theleakage paths between adjacent petticoats 8, are of similar form andshape throughout the length of the built-up structure. In otherrespects, the exterior bushing shown in Fig. 2 corresponds to thebushing of Fig. 1, which yis fully described above.

My invention is, of course, not restricted to any particularapplication, and I desire that the scope shall be limited only by theappended claims.

I claim as my invention:

1. An insulating structure comprising a series of superposed andtelescoped insulating tubular members to provide double walls, aplurality of laterally extending annular conducting members, the innerrim of each being interposed between adjacent pairs of said insulatingmembers, and additional insulating bodies bridging the spaces betweenthe, said adjacent conducting members.

2. An insulating structure comprising a series of superposed insulatingtubular members, the lower portion of each overlapping with the upperportion of the next succeeding one to provide double walls, a pluralityof annular conducting members having their inner rims interposed betweenadjacent pairs of said insulating members, and additional insulatingbodies bridging the spaces between the adjacent conducting members, andbeing shaped to substantially conform to the electrostatic flow linesextending between adjacent conducting members.

3. An insulating bushing comprising a series of superposed insulatingtubular members having elbows formed intermediate]` their ends, aplurality of annular conducting members engaging the tubular members atsaid elbows, and insulating ybodies bridging the spaces between adjacentconducting members, said conducting members extending laterally beyondthe insulating material.

4. An insulating bushing comprising a series of superposed andtelescoped insulating tubular members having elbows formed intermediatetheir ends, a plurality of laterally and downwardly extending annularconducting members engaging said elbows of the insulating members, andinsulating material so shaped as to conform to the electrostatic Howlines bridging the spaces between adjacent conducting members.

5. An insulating bushing comprising a series of superposed insulatingcylinders tending laterally beyond the `porcelain 10 having elbowsformed intermediate their members.

ends, a plurality of annular conducting In testimony whereof, I havehereunto members engaging the cylinders at said subscribed my name this22nd day of May, elbows, and additional porcelain members 1914.

bridging the spaces between adjacent con- RAY P. JACKSON. ductingymembers in order to providel leak- Witnesses: A

a ge paths therebetween of permanently high V. K. WILLIAMS,

resistance, the said conducting members eX- B. Bv

